A Novel Platform for Secretory Production of Recombinant Proteins in Saccharomyces Cerevisiae

In spite of the higher preference of Saccharomyces cerevisiae as an expression host for the secretory production of recombinant proteins, only a limited number of secretion signals are available. To expand the repertoire of effective secretion signals in S. cerevisiae, we developed a target protein-specific translational fusion partner (TFP) screening system that involves recruitment of an optimal secretion signal and fusion partner from genome. Around 4 x 10³ TFP library was constructed from a genomic and truncated cDNA library by using the invertase-based signal sequence trap technique. The efficiency of the system was demonstrated using two rarely secreted proteins, human interleukin (hIL)-2 and hIL-32. Optimal TFPs for secretion of hIL-2 and hIL-32 were easily selected, yielding secretion of these proteins up to hundreds of mg/L. Moreover, numerous uncovered yeast secretion signals and fusion partners were identified, leading to efficient secretion of various recombinant proteins. Selected TFPs were found to be useful for the hypersecretion of other recombinant proteins at yields of up to several g/L. This screening technique could provide new methods for the production of various types of difficult-to-express proteins